1. Field of the Invention
The present invention relates to a fabric-like array of electronic and/or optoelectronic circuitry and a method for forming the fabric-like array in two- or more dimensions.
The present invention concerns an apparatus comprising electronic and/or optoelectronic circuitry for implementing electronic and/or optical functions, wherein the circuitry is realized and/or integrated in two or more dimensions and a method for method for realizing and/or integrating circuitry in two- or more dimensions, wherein the circuitry comprises elements in the form of wires, fibres, ribbons, strips or multicomponent filaments and/or combinations thereof, wherein said circuitry is electronic and/or optoelectronic circuitry for implementing electronic and/or optical functions in an apparatus comprising circuitry of this kind.
More particularly, the present invention relates to integrating filament-like electrical and/or optical conduits into two- and three-dimensional physical structures for creating electronic or optoelectronic circuitry, sensors and/or emitters. The spatial extent or region of influence of such circuitry, sensors and/or emitters is controlled by specific definition of the electrical and/or optical properties of the individual filaments and how they are incorporated into the structures.
In particular, the present invention concerns integrating filament-like electrical and/or optical conduits into two- and three-dimensional physical structures for creating electronic or optoelectronic circuitry, sensors and/or emitters. The spatial extent or region of influence of such circuitry, sensors and/or emitters is controlled by specific definition of the electrical and/or optical properties of the individual filaments and how they are incorporated into the structures.
2. Background Information
The development of integrated circuits on silicon and semiconductor compound materials has revolutionized the electronic industry. However, the ever increasing complexity and costs of higher integration technology has generated interest in novel materials and methods.
The development of integrated circuits on silicon and semiconductor compound materials has revolutionized the electronic industry. However, the ever increasing complexity and costs of higher integration technology has generated interest in novel materials and methods.
For instance, progress in conductive polymers and organic materials has led to novel displays, diodes and field-effect transistors using these materials. See G. Horowitz “Organic field effect transistors” Adv. Mat. Vol. 10, pp. 365–377 (1998); D. Pede & al. “A general-purpose conjugated-polymer device array for imaging” Adv. Mat. Vol 10, pp. 233–237 (1998); R. H. Friend et al. “Electroluminescence in Conjugated ‘Polymers”, Nature 397, pp.121–128 (1999).
Thin-film-based inorganic semiconductor technologies compatible with low temperature-resistant packaging and substrate materials are under rapid development, and include amorphous silicon as well as polysilicon and microcrystalline silicon. In this connection, see, e.g. J. G. Blake & al., “Low-temperature polysilicon reshapes FPD production”, Solid State Technology, pp.151–161 (May 1997).
Defect tolerant architectures have been proposed to circumvent the problems of trying to produce defect free chips, for instance by J. R. Heath & al., “A defect-tolerant computer architecture: opportunities for nanotechnology”, Science, Vol. 280, pp. 1716–1721 (Jun. 12, 1998).
Such novel materials and methods open up entirely new opportunities in electronics and optoelectronics that extend much beyond providing an evolutionary route to alleviating problems and limitations adhering to the present state of the art. Unfortunately, present-day semiconductor-oriented technologies are totally inadequate for exploiting the true potential of these novel materials and methods, and there exist pressing needs for complementing technologies. One area of particular importance is that of gaining freedom from the dominating role of the substrate.
In traditional silicon-based technologies, the electronic functionality is derived from the semiconducting silicon substrate, which severely restricts opportunities for extensions into the third dimension. Furthermore, physical dimensions are restricted, and the traditional lithographic processes provide only limited flexibility with respect to intra-device connectivity. This includes both the physical characteristics of the connecting lines themselves and how they can be positioned throughout the device structures in question. Typically, the substrate and its layered superstructures contain electrical interconnects where electric currents flow in patterned strip- or ribbon-like conducting paths that have been created by subtractive or additive processes.
Subtractive processes are well-known and much used in the semiconductor industry, and involve wet or dry etching whereby conducting material is removed from portions of the substrate. Conducting material is retained in regions where a protective layer has been applied in the patterns desired, e.g. by optical lithography. Typically, all modern microelectronic circuits involve multiple step lithography processes where image(s) of parts or all of the circuitry, mostly wires, and devices are transferred to the substrate. This requires careful register between each step, the more so as the features become smaller and smaller. The substrate must be extremely flat and rigid. Furthermore, the circuitry cannot be continuous through this approach. Several chips have to be made individually on one wafer at the time. Furthermore, the integration of electronic and optoelectronic circuits is extremely difficult by such methods. It would therefore be highly advantageous to find microcircuit fabrication methods which eliminate lithographic processes altogether and allow for flexible continuous fabrication of electronic and optoelectronic circuits.
Additive processes have hitherto been less used in electronic circuits, but may become important in the future. They include microprinting and micromolding of conducting inks or solid state conductors, screen printing and more exotic means such as laser mediated deposition (see, e.g.. H. Yabe & al., “Direct writing of conductive aluminum line on aluminum nitride ceramics by transversely excited atmospheric CO2 laser”, APL 71 2758 (1997)).
The present invention introduces the concept of woven electronics as a new generic approach to making and assembling electronic and optoelectronic devices and apparatus, in particular by exploiting opportunities that arise with the advent of novel electronic materials. This implies a radical departure from present state of the art.
This is substantiated by searches performed in the literature have to a small extent been able to identify any relevant prior art. Yet there is for the sake of completeness in order to briefly discuss patent documents which touch upon circumstances of general relevance for the present invention.
Thus there is from DE 31 16 348 A1, “Elektrische Verbindungseinrichtung” (Oscar Alonso, USA), and WO96/38025 A1, “Composite materials” (Geroge William Morris, Great Britain) known substrates which incorporate woven layers with electrical conduits. The latter are, however, applied after the weaving process has been finished, by methods such as etching, printing or electron sputtering.
JP-05299533, “Electronic part mounting board and electronic part device using the same” (Ohigata Naoharu, Japan) discloses a woven structure incorporating conducting wires interspersed with electrically insulating filaments. However, the focus is here substantially on providing alternative substrates to replace circuit mounting boards subjected to thermal and mechanical stress and the publication discloses in principle neither a new kind of functionality nor novel apparatuses which can be seen to be of relevance for the present invention.
Further can be mentioned U.S. Pat. Nos. 4,913,744 and 5,902,416 (both H. Hoegel & al.) which concern wire-like, band-like and rod-like solar cells which in at least one embodiment are provided in a woven structure. It is stated that the separate solar cells in the woven structure can be electrically connected at the underside of the crossing in the web with a counter-electrode in order to realize charge transfer between centre electrodes of the solar cells. It is also stated that the contact effect can be improved by a compression of solar cells in the form of wires or the crossing points either by thermal treatment or by use of electrically conducting adhesive. The object in this case is to achieve an improved arrangement of the solar cells, including among other by allowing the realization of tandem cells.
Generally there is both from the patent literature and other literature known to include conducting metal wires by weaving into a large number of objects. This includes meshes, which e.g. act as electrical shielding in housings, and electrodes and filters in material science. Metallic fabrics and metallic embroidery are used to make decorative and protective clothes. Conducting wires are integrated in fabrics to provide clothing and furniture, which prevent the formation of electrostatic charge or alternatively used for providing electrical heating. In so-called “smart clothes” such woven structures may for instance be used for connecting or providing the clothes and apparels with electronic devices and sensors. For instance can in this connection be mentioned U.S. Pat. No. 5,906,004 (Lebby & al.) (assigned to Motorola Inc.) which discloses a textile fabric with a number of electrically conducting fibres, which are able to provide either a wire-based or wireless connection between the textile fabric and a portable electronic device. The intention is that the textile fabric may be used for manufacturing functional clothes and other objects of woven textile fabric with the intention of increasing the functionality of the clothing or the functionality of the object. Typically are electrically conducting fibres disclosed in the capacity of providing an interconnection to a portable electronic device of some kind or other. Concerning the development in this area it can also generally be referred to S. E. Braddock and M. O'Mahony, “Techno Textiles—Revolutionary Fabrics for Fashion and Design”, ch. 2, Thames and Hudson, New York (1998). Summing up a survey of the prior art illuminated by the above-mentioned patent literature and other literature shows that the use of a woven structure which provides electrically conducting and electrically screening functions is per se well-known and the same is also the case for uses of such structures for providing electrical connections between discrete, separate or surface-mounted devices. Inherent features of such woven structures for providing a more comprehensive electronic or optoelectronic functionality is not touched upon at all.
To conclude, in order to realize the potential in a wide range of emerging electronic and optoelectronic materials and methods, there is a need for complementing technologies which are not within the present-day state of the art. Prominent among such technologies are those that can provide electrical and optical interconnections in two and three dimensions, with high spatial density, high signal speed potential and small crosstalk. Also prominent are technologies and materials suitable as structural platforms for large area electronics and/or three dimensional device architectures.